• Producer : R. Venkataraman
• Director : Sankalp Reddy
• Story : Azad Alam
• Writer : Azad Alam , Gangaraju Gunnam
• Screenwriter- screenplay : Sankalp Reddy , Gangaraju Gunnam , Niranjan Reddy
• Actor : Rana Daggubati , Kay Kay Menon , Atul Kulkarni
• Actress : Taapsee Pannu

In November, 1971, India and Pakistan are on the verge of declaring war on each other, as a result of the refugee crisis precipitated by the Pakistan Army under Operation Searchlight. The Indian Navy and RAW decipher a secret code sent from Pakistan to East Pakistan (modern-day Bangladesh), relating to a possible attack on an Indian naval vessel. The Navy deduces that the target may be INS Vikrant, India's sole aircraft carrier. The top command dispatches the submarine S21, under the command of Cmdr. Ranvijay Singh for recce missions. To temper Singh's belligerent tendencies, the Indian Navy Admiral assigns Lt. Cmdr Arjun Varma to S21, with orders to ensure that Singh does not confront any Pakistani warships and trigger a war. The Navy's top command soon learns that the Pakistan Navy has dispatched PNS Ghazi, under Cmdr. Razak Khan, to the Bay of Bengal to confront Vikrant. Meanwhile, to divert the attention of the enemy, Ghazi torpedoes an Indian merchant ship. The attack is picked by S21, which races to the scene. Noticing survivors in the wreckage, Arjun jumps into the sea and manages to rescue a girl child and a woman, both of whom are Bengali refugees. During surveillance, S21 acquires a sonar signal of Ghazi. Singh believes that they should track down Ghazi and attack, while Arjun obstructs, reiterating his instructions. Singh then orders the ship's EXO, Lt. Commander Santosh Devraj to conduct a drill and target Ghazi while doing so, despite Arjun's protests. They fire a torpedo, which misses Ghazi narrowly, thus alerting them of their presence. Aware of the enemy's presence, Razak orders his crew to head towards Visakhapatnam Port at full speed and to set up mines en-route, planning to destroy S21. S21 pursues Ghazi's path and realizes at the last moment that it is headed into mines. Singh and Arjun frantically attempt to change its course but a mine explodes in the stern and damages most of the sub's batteries, propellers and circuits. The sub blows open many leaks, with the forward torpedo compartment flooded, crippling the sub and barring it from firing its forward torpedoes. Singh dies while trying to save Arjun, as S21 sinks to the sea-bed. Arjun, now in command of the sub, regroups and work towards reviving S21. They manage to clog the sub's leaks and pumps the excess water out, before holding a final farewell for Singh. The crew noticed that the vessel is incapable of moving in any direction, except upwards or downwards. Since they are unable to chase Ghazi, the crew artificially trigger one of the naval mines in its vicinity to lure Ghazi to their position. Razak, believing S21 is still operational, orders his crew to turn around to sink S21. Arjun and Devraj plan to lure Ghazi within its range of firing, but a suspicious Razak orders Ghazi's course to be changed at the last minute. Ghazi, now having the ability to attack S21, fires six torpedoes, all of which are avoided by S21 through depth changing maneuvers, much to Razak's frustration. S21 dives to 350 m, in order to slip from Ghazi's sonar range despite being designed for a maximum of 250 m depth. With very limited battery support, Arjun instigates Ghazi into attacking by transmitting his crew singing 'Saare Jahaan se Achchha' and the Indian National Anthem. Riled up by S21's defiance, Razak orders another torpedo attack on S21, for which Ghazi will have to turn by port 180 degrees. Arjun dives into the flooded forward compartment to manually trigger the torpedoes, successfully managing to do so. Ghazi also launches its torpedo at the same time. The torpedo launched by Ghazi misses S21 narrowly, but it is hit by S21's torpedo and disintegrates in the water, killing the entire crew. S21 surfaces and the crew manages to save Arjun from the flooded compartment in the nick of time. S21 is later saved by a patrolling Indian Navy vessel. The ending titles narrate the mysterious circumstances about Ghazi's fate, with its sinking credited to the actions of INS Rajput. It also mentions that in the aftermath of Ghazi's sinking, India and Pakistan had declared war on each other, which would ultimately result in India's victory, Pakistan's surrender and the creation of Bangladesh.